I too experienced this issue and was beyond frustrated. I came across a suggestion by another owner of the S9+ on a different forum and found the suggestion to solve my problem (hopefully for you it works as well)!
Here's what I did: Settings< Notifications< Advanced (top right-hand corner)< Turn your contacts to "allowed"
I really hope this works. For the amount of money paid for the S9+, it's shameful to have such a minor yet, important feature make it a dreadful purchase.
Thanks but doesn’t work for me mine is already on allowed.
Have you tried restarting the phone as be careful mine works with the spam protection on but as soon as I restart that’s it it goes again. So have to leave it off
I cant believe Samsung have gone quiet on this like other problems reported on the forum I guess
This was reported as a problem on the 3rd April on here but it's highly likely Samsung were made aware of the issue before that. Its now the 14th May and it still hasn't been fixed!! As the primary role of the S9 is... Being a telephone, this is extremely poor. Is there any update as to when the S9's core function will work properly please